Are street clocks air tight?

Discussion in 'Tower, Monumental & Street Clocks' started by GregS, Jan 10, 2016.

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  1. GregS

    GregS Registered User

    Sep 4, 2008
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    I am building a small street clock. The visible dial is 24 inches across. My question is whether the space between the glass/crystal and the dial needs to be airtight. I am concerned that moister will get inside and condense on the glass invoking all the bad things moisture is known for.

    What do your think? I'd love to hear your thoughts/experiences!

    Thank you.
    Greg
     
  2. Jim DuBois

    Jim DuBois Registered User
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    Well, they are not air tight but the really do need to be water tight. Air will circulate up the column and into the head of the clock and ultimately the dials. It is incumbent to keep the water out at all times in my experience, so glazed glass and tight bezels are greatly preferred. Some fair number of street clocks had wood bezels and they usually rot over time as they don't remain water tight as paint fails and wood shrinks and expands. You might find Electric Time's website useful.
     
  3. GregS

    GregS Registered User

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    Thanks for insight Jim. I always read your posts with interest and respect your experiences and value your advice. My bezel is made of hardwood. It's not big, only 32 inches across. Expansion/contraction/rot have weighted heavily on mind. So far, my plan is to apply woodlife coppercoat (copper naphthenate) to the bare wood and then coat it with fiberglass resin before applying primer and paint. But you bring up a good point. If any joint fails or new cracks develop that would expose bare untreated wood. I'm not sure how to combat that.

    I bought the movement/hands from Electric Time but have been reluctant to email questions even though this is a personal project for my home. I know Thomas posts here so maybe he will weigh in.

    My goal is to make it as maintenance free as possible.

    Thanks!
    Greg
     
  4. ElectricTime

    ElectricTime Registered User
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    [FONT=&quot]We are required by our UL listing to add weep holes in the bezel. Any clock will accumulate condensation - especially a free standing street clock which goes through large temperature changes. Accumulated moisture in the area between the crystal and the dial will condensate out when the temperature drops below the dew point.[/FONT]
    [FONT=&quot] [/FONT]
    [FONT=&quot]So the short answer is - put weep holes in - to keep the moisture from accumulating.[/FONT]
    [FONT=&quot] [/FONT]
    [FONT=&quot]BTW - I see a lot of old street clocks - very few with wooden bezels. The ones that have survived are typically in a very dry location - like Reno NV. I do think with modern finishes you will be able to make a wood bezel last a long time - or as another option could you use http://www.azek.com/ ?[/FONT]
     
  5. Tim Orr

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    Good afternoon, Greg!

    We're working on a couple of McClintocks from about the time of WWI here in Boulder and Colorado Springs, and they both are open to the air, in part because they have chimes inside their cases. There are vents along the bottom to let the sound out, and nothing else is even remotely airtight.

    Given the heating and cooling from weather changes, being airtight could, I should think, be a problem, with the large amount of empty space inside. I wouldn't counsel making cases "watertight" either, but rather, using a good design that prevents rain or snow melt from getting inside by directing it to flow away and off, and sealing obvious entry points against wind-blown water entry.

    There's also the idea of deliberately using an incandescent light inside, whose heat could drive out some of the moisture. With incandescents becoming harder and harder to come by, it might take an actual heating element of some sort. Heat tape for home water pipes comes to mind. There are even commonly available thermostats for heat tape, to turn it on when the temperature drops below about 45 degrees.

    Good luck!

    Best regards!

    Tim Orr
     
  6. Jeremy Woodoff

    Jeremy Woodoff Registered User
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    There is also a treated pine lumber, called acetylated wood (www.accoya.com) that machines and takes finishes like ordinary wood, but is guaranteed against rot or deterioration for a very long time (25 years, or possibly now 50 years) in an outdoor environment without any coatings at all. It may take some doing to obtain it, but may be worth the effort.
     
  7. ElectricTime

    ElectricTime Registered User
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  8. GregS

    GregS Registered User

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    When Harrison built his clocks Lignum Vitae wasn't on the red-list of endangered wood species. Besides that stuff is really tough to work. :D

    Jeremy, I looked at pressure treated woods but the only thing readily available was the big box lumber yard variety of mixed pine. I guess I didn't go that route because the wood is always so wet and it could be years before it shrunk and stabilized. The link you provided is very interesting, but I agree, getting some of that stock in small quantities at a reasonable price would be difficult.

    Besides, the bezel has already been made.

    A month or so ago I got a little antsy and picked up about 40 lineal feet of 1x6 poplar. Cut it into lengths with 22.5 degree angles and glue it all up into 4 overlapping layers using water proof glue. Mounted it on a large sheet of plywood with a center block and used a large home made router circle cutting jig to route out everything that wasn't a clock bezel. :D

    Thomas, thanks for the letting me in on the weeper holes. Condensation on the crystal is exactly what I was worryed about. I don't suppose you'd be willing to say how big the hole(s) are in your bezels with 24 inch sight opening.... I am thinking a quarter inch with the hole pointing straight down at the six o'clock position. Do you agree or.... ?

    Here it is while ponder the rest of the story (and wait for spring :D )

    Thank you so much for all of your help and interest!! --Greg

    Img_1285.jpg Img_1292.jpg Img_1310.jpg
     
  9. FDelGreco

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    #9 FDelGreco, Jan 28, 2016
    Last edited by a moderator: Dec 29, 2017
    Poplar is terrible for outdoor use. I once made a garden arbor out of poplar - and another one exactly the same size and shape - out of redwood. I primed and painted both with high quality oil based materials. The poplar arbor rotted away in a couple of years. The redwood is still in good condition after more than 15 years.

    Most any rainforest wood will work great, but if you don't want to use it you can use cypress. I've made tower clock hands out of primed and painted cypress, exposed directly to Cleveland OH weather and they have held up for more than 15 years.

    If you use the poplar bezel, you'll be making another one in a few years.

    Frank
     
  10. gvasale

    gvasale Registered User
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    You could use UHMW. No glueing up and machines easily. Paintable with the proper paint.
     
  11. Jim DuBois

    Jim DuBois Registered User
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    Since you have already done the work in poplar it might be good to consider using epoxy resin from the boat building craft to seal up the surfaces of the entire assembly. It is used extensively these days in building or restoring wooden boats. It is pretty easy to use, it is free flowing, fills the wood surface nicely making it more or less impermeable to water, it can be painted and will withstand weather /water for a very long time....
     
  12. GregS

    GregS Registered User

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    Quoted from my earlier post (#3)

    The Woodlife Coppercoat is a preservative and bare wood coated with it is rated for below ground protection. When I wrote 'fiberglass resin" I really should have written marine grade epoxy resin. I haven't yet purchased any as I'm still researching products. I have toyed with a contraption to spin the bezel very slowly so that when I apply the epoxy it will self level as it rotates. I've done this before on relative small items with very good results. The coating then was a two part clear resin for doing table tops. I am hoping the marine epoxy will act the same.

    And to top all that I was thinking maybe I could get an auto shop to spray it for me using a good urethane auto paint.

    The clock will not be free standing, but instead will be mounted to a wall that will provide north, north-west protection from wind, rain and snow. The dial facing the sun which keeps that side of the building dry and when it does get wet it is always the first to dry out.

    So I'm hoping will all of this the clock will last for many, many years.

    Fingers crossed. :D

    Comments?
     
  13. ElectricTime

    ElectricTime Registered User
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  14. GregS

    GregS Registered User

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  15. GregS

    GregS Registered User

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    Just an update on my clock project. The clock is finished and installed (and yes, the neighbors think I'm crazy, but they all seem to like it).

    All the wood parts (bevel and mounting plate) were finished to size, then all the necessary holes were drilled, then the entire surfaces were treated with a copper based wood preservative. Next everything was completely covered with two coats of System Three marine grade epoxy. Finally a coat of marine base primer followed by two coats of marine grade topcoat paint.

    The dial art work was created using turbocad software to create the roman numerals and chapter ring. Then the drawing was exported to Adobe Illustrator and finished with the wording. The drawing was then printed onto aluminum sheet, 24 1/2 inches in diameter.

    The 'crystal' is 3/16" thick tempered glass with a UV coating on the inside surface to help protect the dial from UV exposure.

    The bezel is 33 1/2 inches across the flats and the whole thing weights 33 lbs.

    The movement comes from Electric Time Inc and is completely controlled via the electronic controller which is mounted in far corner of the garage. It can reset the clock in case of a power failure and adjust the clock to accommodate daylight saving time changes.

    A lot of work was done in the attic space where the clock went. The wall received additional bracing and all the holes for mounting were drilled from the inside prior to installation day.

    All in all this was a lot more work then I ever imagined it would be but I had a really good time building it. Really makes you appreciate what the guys that make real tower clocks must go through.

    crazy eh?

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  16. gleber

    gleber Registered User

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    Not at all. That's a modern heirloom that you should be proud to have created. If that were in my neighborhood, I would be so jealous. I keep teasing my wife and daughter that I'm going to build a replica of this http://www.waymarking.com/waymarks/WMDEDP_Gap_Clock_Tower_Gap_PA in our backyard every time we drive by it. I'm going to have a hard time sleeping tonight thinking about doing something like this. Good for you for getting it done!

    Congratulations!

    Tom
     

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